In order to radiate heat generated in a heating body such as an electronic component, there is a cooler in which a refrigerant of a fluid such as cooling water flows through a flow path which is in thermal contact with the heating body. In such a cooler, in order to improve a cooling efficiency, for example, in JP-A-2014-107119, JP-A-8-116189, JP-A-2014-20115, and JP-A-2014-72395, a plurality of ribs or fins are provided within a flow path and the flow path is divided.
In JP-A-2014-107119, the plurality of ribs are provided within the flow path in parallel or oblique to a flow direction of the refrigerant. In JP-A-8-116189, in order to agitate the cooling water within the flow path, a narrow flow path having a narrow cross-sectional area and a wide flow path having a wide cross-sectional area are alternately disposed and the plurality of fins are provided within each flow path in parallel or oblique to the flow direction of the refrigerant.
In JP-A-2014-20115, in order to promote a turbulent flow of the refrigerant within the wide flow path being in thermal contact with the heating body, a plurality of corrugated fins are respectively provided within the wide flow path at predetermined intervals in the flow direction of the refrigerant and in a width direction of the flow path. In JP-A-2014-72395, a plurality of columnar fins are disposed within the wide flow path being in thermal contact with the heating body in a staggered manner and a plurality of protrusions are provided on an inner surface of the wide flow path at predetermined intervals in the flow direction of the refrigerant.
Conventionally, for example, in order to improve the cooling efficiency, a cross-sectional area of the flow path portion being in thermal contact with the heating body is wider than a cross-sectional area of other flow path portions such as inlet and outlet ports of the refrigerant that is a fluid. However, in a case where the refrigerant flows from the narrow flow path having the narrow cross-sectional area to the wide flow path having the wide cross-sectional area, the refrigerant flows through a part of the wide flow path and the refrigerant may not widely spread to the wide flow path. In addition, in the wide flow path, a difference occurs in a flow speed of the refrigerant between a certain portion and the other portions, and a vortex flow or a reverse flow of the refrigerant occurs. Therefore, a pressure loss of the refrigerant increases and the refrigerant flow in the flow direction may be stagnant. Furthermore, as in the related art, even in a case where the turbulent flow of the refrigerant is promoted by the plurality of ribs or fins in the wide flow path, the refrigerant flow in the flow direction may be stagnant. As described above, if the refrigerant flowing from the narrow flow path does not widely spread to the wide flow path, or the refrigerant flow from the narrow flow path to the wide flow path is stagnant, the cooling efficiency of the heating body by the refrigerant flowing through the wide flow path decreases.